Methods for making construction material using enzyme producing bacteria

ABSTRACT

There is provided a method for producing construction material utilizing loose pieces of aggregate, enzyme producing bacteria, an amount of urea and an amount of calcium ions. A first solution is prepared which includes urease which is formed by enzyme producing bacteria. A second solution is prepared which includes urea and calcium ions. The first and second solutions are added to the loose aggregate. The calcium ions contribute to the formation of calcium carbonate wherein the calcium carbonate fills and bonds between at least some of the gaps between the loose pieces of aggregate forming a solid construction material.

RELATIONSHIP TO PRIOR APPLICATION

This is a U.S. non-provisional application relating to and claiming thebenefit of U.S. Provisional Patent Application Ser. No. 61/328,233,filed Apr. 27, 2010.

BACKGROUND OF THE INVENTION

This invention relates to methods for producing construction material.More particularly, it relates to methods for producing constructionmaterial using enzyme producing bacteria.

The built environment is primarily constructed using a limited paletteof traditional materials: clay, concrete, glass, steel, and wood. Thesetraditional materials contain a high-embodied energy, with components ofconcrete and steel mined from non-renewable resources. Although wood canbe grown and harvested in a renewable manner, harvesting, processing andtransportation greatly contribute to carbon dioxide production anddepend on large amounts of energy and fuel resources. Approximately,forty-percent of global carbon dioxide is linked to the constructionindustry, primarily due to material production and disposal.Biologically grown materials can be pollution free and contain a lowembodied energy, if produced as part of a local ecosystem.

Commonly used throughout history, masonry construction continues to makeup a large part of the built environment, utilized for both load bearingstructures and veneer construction. According to Chaisson, globally,traditional clay brick manufacturing produces over 1.23 trillion unitsper annum with a heavy dependency on non-renewable natural resources.Clay brick manufactured in coal-powered kilns emits approximately 1.3pounds of carbon dioxide per unit. According to Burke, in total, brickmanufacturing emits over 800 million tons of man-made CO₂ each year, andyet represents only one material currently used in buildingconstruction.

Fired clay bricks can be manufactured between 3-20 days, depending onthe equipment and processes used. This range represents modern automatedfactories able to process bricks without manual labor, to the clampmethod of bricks stacked around a burning fire used in many developingnations.

As an alternative to load bearing fired clay masonry, Concrete MasonryUnits [CMU] are widely used as they are more economical, faster tomanufacture and can serve as a structural typology for globalconstruction. Comprised of concrete, these units are made with Portlandcement, large aggregate and sand filler. According to Hanley of theUnited States Environmental Protection Agency, global carbon dioxide(CO₂) emissions from cement production were approximately 829 millionmetric tons of CO₂ in 2000.

According to DeJong, Natural cement is created through chemicaldeposition and chemical processes associated with weathering, and can befound in various locations on the earth's crust. The formation ofnatural sandstones is primarily attributed to the precipitation ofcalcite cement.

Urease producing Sporosarcina Pasteurii a nonpathogenic, common-soilbacterium has the ability to induce the production of calcite through achemical reaction, fusing loose aggregate. A hardened material is formedin a process referred to by Stocks-Fischer as microbial induced calciteprecipitation [MICP]. Applications include environmental stabilizationof contaminated soils, and encapsulation of hazardous and othercontaminants in natural soils and acid mine tailings. Ramachandran andJonkers have proposed the use of microbes to remediate cracks inconcrete structures and the repair of cracks in monuments. According toDeJong and Whiffin, civil engineering researchers in the United States,Australia and the Netherlands have proposed the use of MICP for soilstabilization and erosion control.

SUMMARY OF THE INVENTION

In accordance with one form of this invention there is provided a methodfor producing a solid construction material which preferably is amasonry unit such as brick. A first solution is prepared which includesurease which is formed by an enzyme producing bacteria. Preferably, theenzyme producing bacterium is Sporosarcina Pasteurii, SporosarcinaUreae, Proteus Vulgaris, Bacillus Sphaericus, Myxococcus Xanthus,Proteus Mirabilis, Helicobacter Pylori or a combination thereof. Mostpreferably, the enzyme producing bacterium is Sporosarcina Pasteurii.Preferably, an amount of the enzyme producing bacteria remains in thefirst solution after the urease is formed. A formwork is at leastpartially filled with loose pieces of aggregate wherein gaps are formedbetween at least some of the pieces. Preferably, the aggregate is sand.An amount of the first solution is added to the loose aggregate. Anamount of urea and an amount of calcium ions are added to the looseaggregate. The first solution, the urea and the calcium ions may beadded to the loose aggregate simultaneously or at different times or ina different order. The calcium ions contribute to the formation ofcalcium carbonate. The calcium carbonate fills at least some of the gapsbetween the loose pieces of aggregate, bonding to the aggregate andthereby forming a solid material. The solid material is removed from theformwork. Preferably, the formwork is rotated and additional amounts ofthe first solution, the urea and the calcium ions are added to the looseaggregate prior to removing the solid material from the formwork.

In accordance with another form of this invention there is provided amethod for producing construction material. A first solution is preparedwhich includes urease, which is formed by an enzyme producing bacteria.A first layer of loose pieces of aggregate are applied to a substratewherein gaps are formed between at least some of the pieces within thefirst layer. A first amount of the first solution is applied to thefirst layer. An amount of urea and an amount of calcium ions are appliedto the first layer. The first solution, the urea and the calcium ionsare applied to the first layer simultaneously or at different times orin a different order. A second layer of loose pieces of aggregate areapplied to the first layer so that gaps are formed between at least someof the pieces of the second layer and between at least some of thepieces at the boundary between the first and second layers. A secondamount of the first solution is added to the second layer. A secondamount of the urea and a second amount of calcium ions are added to thesecond layer. The second amount of the first solution and the secondamount of the urea and the second amount of calcium ions are applied tothe second layer simultaneously or at different times or in a differentorder. The calcium ions contribute to the formation of calciumcarbonate. The calcium carbonate fills at least some of the gaps betweenthe loose pieces of aggregate, bonding to the aggregate and therebyforming a solid material.

In accordance with another form of this invention there is provided amethod for producing construction material using a computer numericalcontrolled (CNC) deposition machine having at least first, second andthird containers. A first solution is prepared which includes ureaseformed by enzyme producing bacteria. A second solution is prepared whichincludes calcium ions. Preferably, the second solution also includesurea. The first container is at least partially filled with the firstsolution. The second container is at least partially filled with thesecond solution. The third container is at least partially filled withan amount of loose pieces of aggregate. A first layer of loose pieces ofaggregate from the third container is applied to a substrate. A firstamount of the first solution is applied from the first container to thefirst layer. A first amount of the second solution from the secondcontainer is applied to the first layer. A first amount of urea isapplied to the first layer. The first amount of the first solution, thefirst amount of the second solution, and the first amount of urea areapplied to the first layer simultaneously or at different times or in adifferent order. A second layer of loose pieces of aggregate from thethird container is applied to the first layer. A second amount of thefirst solution from the first container is applied to the second layer.A second amount of the second solution from the second container isapplied to the second layer. A second amount of urea is applied to thesecond layer. The second amount of the first solution, the second amountof the second solution, and the second amount of urea are applied to thesecond layer simultaneously or at different times or in a differentorder. The calcium ions contribute to the formation of calciumcarbonate. The calcium carbonate fills and bonds between at least someof the gaps between the pieces of aggregate whereby the first and secondlayers are bonded together and a solid material is formed.

In accordance with yet another form of this invention there is provideda method for producing construction material. A solution is preparedwhich includes urea, calcium ions and enzyme producing bacteria. Theurea and the enzyme producing bacteria react to form urease. The calciumions in the solution contribute to the formation of calcium carbonate.An amount of loose pieces of aggregate are provided whereby gaps areformed between at least some of the pieces. The calcium carbonatecontaining solution is added to the aggregate. The calcium carbonatefills at least some of the gaps between the loose pieces of aggregate,bonding to the aggregate and thereby forming a solid material.

As used herein, the term “bacteria” includes a single type of bacteriaor a mix of multiple types of bacteria. Also as used herein, the term“formwork” includes frames, forms, molds, and other apparatus which maybe used to hold loose pieces of aggregate together before the pieces arebonded in accordance with the teachings of this invention. Also as usedherein, the term “solid construction material” includes constructionmaterial which is porous and non-porous.

This invention utilizes MICP and defines methods to fabricate full-scaleconstruction materials, including load bearing masonry which may bepre-cast. The benefits of a construction material that can be “grown” gobeyond issues of economy and sustainability. As this is a material madeby aggregation, additional materials can be added to the composite foradditional performance traits, such as fibers for additional strength,Titanium Dioxide [TiO₂] for pollution absorption, glass beads for thetransmission of light, and/or air-entrained aggregates for insulation.MICP materials mimic the properties of natural sandstone and arecomposed of similar crystalline formations.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter which is regarded as the invention is set forth inthe independent claims. The invention, however, may be better understoodin reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a formwork which may be used inconnection with the manufacture of construction material in accordancewith the teachings of the invention.

FIG. 2 is an exploded pictorial view showing another embodiment of theformwork of FIG. 1.

FIG. 3 is a flow chart showing steps for the production of constructionmaterial in accordance with one embodiment of the invention.

FIG. 4 is a side elevational view showing multiple layers of bondedaggregate formed using the embodiment of FIGS. 2 and 3.

FIG. 5 is a flow chart showing steps for the production of constructionmaterial in accordance with another embodiment of the invention.

FIG. 6 is a side elevational view also showing multiple layers of bondedaggregate formed using the embodiment of FIGS. 5 and 6.

FIG. 7 is perspective view of a computer numerical controlled depositionmachine which may be used to produce construction material in accordancewith the teachings of an embodiment of the invention.

FIG. 8 is a pictorial view showing details of a portion of the computernumerical controlled deposition machine shown in FIG. 7.

FIG. 9 is a perspective view showing details of an additional portion ofthe computer numerical controlled deposition machine shown in FIG. 7.

FIG. 10 is a photomicrograph showing bonding of certain gaps betweenloose pieces of aggregate with calcium carbonate.

FIG. 11 is a perspective view of a screen which may be used to filterpieces of aggregate material in accordance with the teachings of thisinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Sporosarcina Pasteurii, a nonpathogenic common soil bacteria, has theability to induce a cement material that can fuse loose aggregate, suchas grains of sand. Other aggregates such as glass beads, recycled glassfoam, fly ash composite, soil, small stones, basalt, fibers, andmixtures of the above may also be used. Ideally, local aggregate wouldbe used from, distilled directly from the location where the units areto be manufactured. If the pieces of aggregate, such as sand, are fusedin a formwork or deposited in layers and treated in accordance with theteachings of this invention, construction materials, which arepreferably masonry units such as brick, may be manufactured. Theteachings of this invention could further be used to produce pre-castelements such as panels, columns, tiles, counter-tops, and/or any otherconstruction unit commonly produced using clay, concrete, and/or stone.A hardened material is formed in a process known as microbial inducedcalcite precipitation [MICP]. The bacteria may be mixed in a solution ofurea and calcium chloride. According to Ramachandran, the bacteriaproduce an enzyme, which in this case is urease, and use urea as asource of energy, producing ammonia and carbon dioxide, increasing thepH level of the solution. The rise in pH forms a mineral “precipitate,”combining calcium chloride with carbon dioxide. The bacteria can thenact as nucleation sites, attracting mineral ions from the calciumchloride to the cell wall, forming calcite crystals. The mineral growthfills gaps between the sand grains, biocementing or bonding themtogether. Preferably, the gaps are at least 5 microns in width. Theresulting material exhibits a composition and physical propertiessimilar to naturally formed sandstone.

It is believed that other enzyme producing bacteria that have potentialfor biocementation include Sporosarcina Ureae, Proteus Vulgaris,Bacillus Sphaericus, Myxococcus Xanthus, Proteus Mirabilis andHelicobacter Pylori, although proper concerns should be given topathogenic strains.

This method for manufacturing construction materials through inducedcementation exhibits low embodied energy, and can occur in a range oftemperatures , e.g., below 40° C., substantially less than traditionallymanufactured construction materials. Traditional brick and concreteconstruction is heavily reliant on burning natural resources such ascoal and wood. This reliance results in increased carbon dioxideemissions and a greater dependency on limited energy sources. Theintroduction of a bioengineered building unit using aggregate andnaturally induced cementation offers a natural alternative that may belocally produced and environmentally friendly.

One objective of this invention is to produce a “grown” constructionmaterial, such as a brick, utilizing primarily minerals, MICP and looseaggregate, such as sand.

As collaboration between architecture and microbiology, this inventionenables one to use MICP, in conjunction with local sand aggregate, forthe creation of a “biologically grown” building material, to be used bythe construction industry. “Brick” manufacturing can be achievedutilizing traditional casting methods, or articulated by digital toolingto fabricate layered units with a programmed material composition. Theuse of computer numerical controlled (CNC) manufacturing technologies iseconomically driven as it generates little waste, accommodates a varietyof potential materials, provides a high degree of accuracy, and allowsfor the mass customization of form, consistency, and materialdistribution. The brick can be digitally modeled to specifically andprecisely locate mineral templates for growth, and different sizes ofaggregate for intended performance. Programmed, layered growth allowsfor the ability to vary dimensions within the brick, just as bone variesin orientation and density throughout its length, becoming thicker andthinner in places.

These biological bricks do not require the traditional use of Portlandcement mortar, rather they use the same process during biomanufacturefor connection. During the construction process, the completed bricksmay be “dunked” into a slurry of bacteria, growth media, and/oraggregate prior to placing them together. The bricks fuse over a periodof time as the bacterially induced precipitation bonds the aggregategrains together, preferably with calcite.

This invention enables the reduction of atmospheric carbon dioxide byoffering an alternative to the high-embodied energy traditionallymanufactured construction materials. Employing bacteria to naturallyinduce mineral precipitation, combined with local aggregate and rapidmanufacturing methods, this invention enables the production of a local,ecological, and economic building material for use throughout the globalconstruction industry.

In accordance with one embodiment of this invention, a formwork, such asformwork 10 shown in FIG. 1, is used to contain the aggregate, such assand, while the aggregate is being treated with solution or solutionscontaining urease, calcium ions, urea and preferably, an enzymeproducing bacteria. Preferably, the urease is formed by exposing anamount of urea to the enzyme producing bacteria, such as SporosarcinaPasteurii. Formwork 10 includes first, second, third and fourth verticalwalls 12, 14, 16 and 18, which are connected together forming cavity 20therebetween. Cavity 20 is adapted to receive the loose pieces ofaggregate such as sand. Formwork 10 may also have a floor 22.Alternatively, the bottom of the formwork may be left open if supportedby a porous surface such as soil. Preferably, vertical walls 12, 14, 16and 18 or at least the inside surfaces thereof, are made of anon-reactive, non-porous material such as cast or extruded acrylicresin. This enables one to easily remove the construction material orthe brick from the formwork 10 after it has solidified. In addition, thevertical walls and floor of formwork 10 may have textures to formtextures in the resulting brick.

FIG. 2 shows, an alternative of the formwork of FIG. 1 which is able tobe rotated so that the solutions more fully penetrate into the sand formore uniform cementation. Formwork 24 includes four vertical side walls26 made of non-porous non-reactive material as described in reference toFIG. 1. Cavity 28, formed by the vertical side walls 26, is filled withan aggregate material 30, such as sand. Preferably, the pieces ofaggregate are filtered by a known aggregate filter, such as screen 31shown in FIG. 11, so that specific aggregates with specificconsistencies and make-up may be placed in the formwork. Alternatively,thin layers of aggregate may be added to cavity 28 over time with eachlayer being separately treated with the solutions. The top and bottom ofside walls 26 include moisture seals 32 and 34. A top removable panel 36interfaces with moisture seal 32. The top removable panel is also madeof non-porous non-reactive material. The top removable panel 36 includesa plurality of influent openings 38. A bottom removable panel 40interfaces with moisture seal 34. The bottom removable panel is alsomade of non-porous non-reactive material. The bottom removable panel 40includes a plurality of effluent openings 42. As will be describedbelow, when formwork 24 is rotated 180°, the effluent openings 42 becomeinfluent openings and vice versa. Influent openings 38 and effluentopenings 42 may be connected to hoses (not shown) to permit applicationand drainage of solutions containing urease, calcium ions, urea andpreferably the bacteria. As cementation primarily occurs near the topportion of the aggregate material, that cementation can block thepassage of additional amounts of solution further into the interior ofthe aggregate material. The embodiment of FIG. 2 permits the formwork 24to be rotated, which in this embodiment is 180°, so that the openings 42of bottom panel 40 become influent openings and the openings 38 of toppanel 36 become effluent openings. This rotational feature enablesbetter penetration of the solutions into the aggregate. The use of aplurality of influent openings provides for a more equal distribution ofthe solutions. In addition, the inner faces of the vertical walls 26 andthe panels 36 and 42 may be textured, enabling better physicalconnections during assembly and/or for giving an aesthetic appeal to thebricks. In addition, a positive bump out on the inside surface of one ormore of the vertical walls 26 and/or the inside surface of one or moreof the panels 36 and/or 40, may be provided so that the resulting brickwill have a hollowed out region or regions.

The embodiment of FIG. 2 enables the solutions to be added to theaggregate purely by gravitational means without the requirement tomechanically force the solutions into the aggregate. The rotation offormwork 24 after a number of treatments ensures homogeneity incementation and strength. Calcium carbonate crystals will grow along theaggregate surfaces where solutions are found, due to the surface tensionalong the pore throat formed between the aggregates. Rotation helps toensure the equal growth of calcium carbonate around aggregate particles.The bonding of the calcium carbonate to adjacent aggregate particles isillustrated in FIG. 10. To achieve an even higher cementation depth, theformwork can be rotated along multiple axes for access to all sides. Forexample, if a six sided rectangular brick is desired, there are threepossible axes for rotation. The embodiment of FIG. 2 shows a single axisof rotation. In addition, this rotational method can be used inconjunction with the lamination or layered method which will bedescribed below.

Steps 1 through 8 of FIG. 3 illustrate the rotational method ofmanufacturing the brick. Step 9 of FIG. 3, when combined with Steps 1through 8, illustrates the combination of the rotational method andlamination method. In the lamination method, discrete layers ofaggregate are separately deposited and individually treated with thesolutions.

Referring now more particularly to FIG. 3, in Step 1, a urease producingbacteria is grown as a broth solution. The preferred urease producingbacteria are Sporosarcina Pasteurii, Sporosarcina Ureae, ProteusVulgaris, Bacillus Sphaericus, Myxococcus Xanthus, Proteus Mirabilis,and Helicobacter Pylori. The most preferred urease producing bacteria isSporosarcina Pasteurii in part due to it being non-pathogenic. Inaddition, growth material such as yeast extract or peptone from soy isadded to the broth to help enable the bacteria to multiply. In Step 2,loose pieces of aggregate material, such as sand, is inserted into thecavity 30 of formwork 24 to the desired height. In the laminationmethod, only a relatively thin layer of loose aggregate is added. Gapsare formed between at least some of the pieces of aggregate material. InStep 3, an aqueous solution containing urea and a source of calciumions, such as calcium chloride, is fed to the aggregate material. InStep 4, the urease enzyme broth solution, preferably containing thebacteria, is fed to the aggregate material. Steps 3 and 4 may be donesimultaneously or at different times or in different order. In addition,the urea and the calcium ions may be in the same or different solutions.In Step 5, calcium carbonate crystals form between at least some of thegaps between the loose pieces of aggregate material. In Step 6, it ispreferred that additional aqueous solution containing urea and calciumions is fed to the aggregate material to reach the desired hardness ofthe brick. In Step 7, Steps 5 and 6 may be repeated until a desiredhardness is reached. In Step 8, the formwork 24 is rotated, which in theembodiment of FIG. 2 is 180°. After rotation, Steps 1 through 7 arerepeated. For combining the lamination method with the rotationalmethod, in Step 2, the formwork 24 is not completely filled withaggregate but is only partially filled so as to form a layer. Thesolutions are applied to that layer of aggregate as set forth in Steps 3through 7 and then the formwork may be rotated as set forth in Step 8.Once that layer has reached a degree of hardness, an additional layer ofaggregate is fed to formwork 24 over the top of the hardened layer andSteps 3 through 8 are repeated. Additional layers can also be formed ina like manner.

FIG. 4 illustrates the striations or layers formed by the combination ofthe lamination and rotational methods referred to above. Layers 41, 43,45, 47 and 49 are discrete layers. The sand within each layer is bondedand the sand at the boundaries of adjacent layers is also bonded forminga solid brick. The layering or lamination method allows for a programmedstructure for the brick, for example, larger aggregate and particledistribution. It also allows for homogeneity of cementation. The calciumcarbonate crystals, which form the bonds, are allowed to grow in betweenthe layers so as to bond the layers together. The layering method offabricating biomanufactured construction material allows for greaterconsistency in cementation and possibly over-all structural performance.The layering of the aggregate material allows for programmed structureand distribution of aggregate particle sizes, that is, larger aggregateparticles may be used as structure.

The preferred embodiment of carrying out the layering or laminationmethod is through the use of a computer numerical controlled (CNC)deposition machine, such as a 3-D printer, an embodiment of which isillustrated in FIG. 6, although other means may be employed, includingmanually layering by hand or mechanically layering through massproduction.

FIG. 5 illustrates an embodiment of the lamination or layering method ofproducing construction material. As illustrated in Step 1, ureaseproducing bacteria, such as one of those listed above, is grown in abatch of broth solution with a growth media, such as urea, formingurease. A growth nutrient such as yeast extract or soy peptone is alsoadded to the broth. As shown in Step 2, a layer of loose aggregatematerial is placed in a formwork or spread over a bed or substrate. Asshown in Step 3, an aqueous solution containing urea and calcium ions,which may be obtained from calcium chloride, is fed to the aggregatematerial. The urease solution is fed to the aggregate material. Again,the solutions from Step 3 and Step 4 may be added to the aggregatesimultaneously, at different times, or in a different order. Inaddition, the urea and the calcium ions may be in the same or differentsolutions. As shown in Step 5, calcium carbonate crystals form betweenthe gaps in the pieces of aggregate material. As shown in Step 6,another aqueous solution containing urea and calcium chloride is fed tothe aggregate material. As shown in Step 7, Steps 5 and 6 are repeateduntil a desired hardness is reached. As shown in Step 8, Steps 1 through7 are repeated, thereby forming a number of layers, until a desiredheight and hardness are reached. As shown in Step 9, the hardenedmaterial, with the layers bonded together, is removed from the formwork,the bed or the substrate. Thus, solid layered material is formed fromthe loose aggregate.

FIG. 6 illustrates multiple layers which are bonded together to form theconstruction material which is made by the embodiment of FIG. 5. Theaggregate within layers 51, 53, 55, 57 and 59 are bonded together andthe adjacent layers at their boundaries are bonded together forming asolid brick.

FIG. 7 shows a computer numerical controlled (CNC) deposition machinewhich may be utilized to produce construction material using thelayering or lamination method. Existing computer numerical controlled(CNC) platforms may be used and are commercially available from theMultiCam company (Series 5000 Model 508), although such platforms needto be modified as discussed below. Essentially, CNC deposition machine44 is a MultiCam Series 5000 Model 508 which has been modified by addingthe items shown in FIGS. 8 and 9, and spreader 54 and bed or substrate46 thereto. The use of CNC technology is economically driven as itgenerates little waste, accommodates a variety of potential materials,provides a high degree of accuracy, and allows for large variations.Thus, the individual units of construction material are not bound byrepeatable formwork or conventional forms. Rather, each unit ofconstruction material can either be the same or different depending onthe desired form and utilization. CNC deposition machine 44 is a threeaxes computer controlled printer for producing laminated or layeredconstruction materials utilizing the lamination or layering method ofthe invention. A horizontal platform or substrate 46 is provided. Theplatform 46 may be specified in any dimension in the X and Y axes. Theplatform is supported by a hydraulic lift or other elevating mechanismfor producing movement vertically, i.e., in the Z axis. Gantry 48commands the Y axis and moves along rails 50 and 52 in the X axis byutilizing stepper motors. A dispensing nozzle unit 76 moves along railsin the Y axis by utilizing stepper motors. A microprocessor coordinatesX-axis, Y-axis, and Z-axis movements to accurately locate the printernozzle in 3-Dimensional space from user provided data, such as a digitalmodel. Elongated container 54 holds the loose pieces of aggregate, suchas sand, and serves as the aggregate spreader. Container 54 extendsacross substantially the width of substrate 46.

CNC deposition machine 44 includes solution containment clusters,namely, cluster 56 and another cluster 58. The solution containmentclusters each include three containers, namely, container 60 whichcontains calcium chloride whereby calcium ions are in solution,container 62 which contains urea in solution, and container 64 whichcontains urease enzyme solution which was formed from combining theenzyme producing bacteria, which preferably is Sporosarcina Pasteurii.Normally, container 64 also includes an amount of the bacteria.

FIG. 8 shows container cluster 56 in more detail. Each container 60, 62and 64 includes a motor driven mixer 66. The motor driven mixer keepsthe contained solution homogeneous. Urease enzyme solution container 64also includes a temperature sensor 68 and warming element 70 to maintainoptimum microorganism growth conditions. The urea solution container 62includes a pH sensor 72 and a buffer solution dispenser 74 formaintaining an optimal concentration of hydrogen ions.

FIG. 9 illustrates a dispensing nozzle 76 for each solution containmentcluster, such as cluster 56. Hoses 78, 80 and 82 connect respectivecontainers 60, 62 and 64 to nozzle 76. Urea from container 62 is mixedwith calcium ions from calcium chloride from container 60 in reservoir84 which is received within dispensing nozzle 76. Urease enzyme andpreferably an amount of bacteria are received from container 64 toreservoir 86. Opening 88 and dispensing nozzle 76 are connected to ureaand calcium ions from calcium chloride reservoir 84 for applying ureaand calcium ions to the layer of aggregate which has been deposited onsubstrate 46. Opening 90 connects to urease enzyme reservoir 86 fordepositing urease enzyme solution onto the aggregate material which hasbeen deposited on substrate 46. Computer control valves, such assolenoids, regulate the mixing of urea and calcium ions as the solutionsare released from their respective reservoirs. Computer control valvesalso regulate the release of the solutions from the reservoirs throughtheir respective openings 88 and 90.

The CNC deposition machine 44 operates as follows. Gantry 48 moveshorizontally in one direction across the entire substrate 46 along the Xaxis depositing a single layer of aggregate material from aggregatecontainer 54. Gantry 48 then returns to its initial position. Gantry 48then moves one position along the X axis. The dispensing nozzles 76 movehorizontally in another direction along the Y axis depositing an ureaseenzyme solution and a solution of urea and calcium ions onto individualunits of sand 92, which in this embodiment are rectangular, which isspecified by the user's input. The dispensing nozzles then return totheir initial position. The steps of depositing the solution arerepeated until gantry 48 reaches the end of the X axis whereby one layerof the construction material, such as brick, is formed. Gantry 48 thenreturns to its initial position. As an option, the solutions may againbe deposited on the same layer of sand to achieve stronger cementation.The elevated substrate 46 then moves downwardly one position in the Zaxis. The steps above are repeated until the desired material height isreached. Multiple cemented layers bonded together forming individualunits are thus formed. The uncemented aggregate material, that is theaggregate material which is between individual units 92, is removed fromthe substrate. The layered cemented units are then removed from thesubstrate.

Alternatively, the solution dispenser nozzles and/or containmentclusters may be utilized in conjunction with other computer numericalcontrolled platforms, such as six and seven axes robotic arms, for theprecision location of solutions.

EXAMPLES Example 1 Cementation Tests

Materials

General cementation tests were performed in 60 ml cylinders withaggregate to test various method sequences and aggregate types.Consecutively, multiple formwork tests were performed in the scale of a1:1 construction unit measuring 3.5 inches×2.25 inches×8 inches [88.90mm×57.15 mm×203.20 mm] and a scaled version of a construction unitmeasuring 3 cm×1.5 cm×5 cm.

Sporascarina Pasteurii [DSMZ 33] was inoculated in a “bacteria solution”DSMZ 220 media modified with urea, transferred to plate for colonygrowth and incubated at 25° C. for later use. General “cementationsolutions” were prepared using 0.28% Tryptic Soy Broth made by Scharlau117-333 mM urea [(NH₂)₂CO], 130-187 mM ammonium chloride [NH₄Cl], 25 mMsodium hydrogen carbonate [NaHCO₃], 55 mM calcium chloride [CaCl₂], and1 L of distilled water. Medias were filter sterilized to insure againstcontamination. A concentration of 55 mM calcium chloride dihydrate wasprepared as an aqueous solution for the calcium ions used in thecementation process,

Apparatus Set Up

Three 60 ml syringes were each filled with [A] 5 g Poraver™ 2 mm⁻¹ mm[porous glass beads], [B] 30 g sieved 600-212 microns of locally sourcedsand found in Sharjah, United Arab Emirates [UAE] and [C] 30 g 600-75microns of the same sand. The samples were then vibrated for granularsettlement and plungers were applied to confine the sand in the form.This process also reduces the air between grains of sand, air entrainedin the system could cause a fracture point in the final hardenedmaterial due to the resulting formation of a bubble void.

A flexible 4 mmID silicon hose was inserted into the top of the syringeplunger as an influent line, and another 4 mmID tube was inserted intothe syringe bottom as an effluent line.

The tests were first fed Solution 1 “Bacteria Solution” at a gravityflow rate as approximately three pore volumes [PV] of media. Afterallowing the bacteria to “set” for six hours, the tests were then fedSolution 2 “Cementation Solution” as three PV of media at a gravity flowrate after which the solution was allowed to “set” for 4-12 hrs. Thissequence was alternated for the UAE sand samples. This process continueduntil hardness was reached. The tests were flushed with tap water andallowed to air dry.

All three samples exhibited cementation. The samples were weighed todetermine gained mineral material. After weighing, the samples wereprepared for Scanning Electron Microscopy [SEM] to visually verifycrystal formations and bonded grains of aggregate. FIG. 10 illustratessample C.

Starting Final Gained Sample Weight Weight Weight A Poraver ™  5 g 10.21g 5.21 g B Sharjah 600-212 microns 30 g 39.94 g 9.94 g C Sharjah 600-75microns 30 g 37.07 g 7.07 gEquipment

Bacterial colonies on plates were stored in a 25° C. incubator. Thebacteria solution batches were grown aerobically with an incubatedshaker set at 37° C., 250-300 RPM for 20-24 hours.

A Tinius Olsen H50TK compression-testing machine was used to determinethe compressive strength value of the final hardened material. As anexample, the sand sample [C] reached 16.58 MPa as a compressivestrength. The overall hardness and strength can be increased withadditional cementation solution treatments.

Example 2 Rotation Method

To create a greater strength and more unified cementation throughout theaggregate, a rotation method was developed for a full-scale “brick”form. A batch of bacteria solution was prepared using the same method asexample 1. Simultaneously, a batch of cementation solution set to 7.25pH was prepared using the same media as example 1. 1700 g of non-sterileaggregate in the form of indigenous sand found in Sharjah, UAE wassieved to 2 mm-212 microns and placed into the formwork, after apolyester fiber filter was applied. The formwork was then vibrated toreduce air between the aggregate, another polyester fiber filter wasplaced on top of the dry aggregate, and the formwork top with influentholes was lastly positioned. The formwork is the same as in FIG. 2. Fullscale construction unit formwork in the form of a building unit [3.5inches×2.25 inches×8 inches] was fabricated of 5 mm cast acrylic usingUniversal Systems 50 Watt laser cutter for precise and reusablebreak-away formwork.

15 ml of 55mM CaCl₂ was added to 750 ml of the prepared cementationsolution. The solution was then fed to the formwork via gravity feedthrough the influent holes. As soon as the effluent began to leave theformwork, the effluent valves were then shut off to “trap” the solutionin the formwork between voids in the aggregate. The solution was allowedto set in the formwork for approximately 15 minutes.

750 ml of bacteria solution with live cells was then fed to the formworkvia gravity feed through the influent holes. Effluent was allowed toleave the formwork until the cementation solution reached the end of theinfluent holes after which the effluent valves were then shut off to“trap” the solution in the formwork between voids in the aggregate. Thesolution was allowed to set in the formwork for 4-12 hours.

Another batch of cementation solution with urea and calcium chloride wasprepared and fed to the formwork via gravity feed through the influentholes. As the effluent began to leave the formwork, the effluent valveswere then shut off to “trap” the solution in the formwork between voidsin the aggregate for 4-12 hours. This process was repeated again 5-10times.

The formwork was then rotated 180 degrees along one axis with the bottomof the formwork becoming the top and the top becoming the bottom.

Another batch of cementation solution with urea and calcium chloride wasprepared and fed to the formwork via gravity feed through the influentholes. As soon as the effluent began to leave the formwork, the effluentvalves were then shut off to “trap” the solution in the formwork betweenvoids in the aggregate for 4-12 hours. This process was again repeated5-10 times.

The formwork was then rotated again 180 degrees along one axis with thebottom of the mold now being on top. Rotation and administration ofcementation solution continued until a desired hardness or strength wasreached. The hardened construction material was removed from theformwork, washed with tap water and allowed to air dry.

After the material was dried and weighed, the resulting material washomogenously cemented on all sides. The cemented material wasmechanically split along the center and cementation was verified alongthe cross section of the interior.

Example 3 Slurry Method

The slurry method used the same medias and methods as the above example,with the exception that the two solutions and aggregate were combinedforming an aqueous slurry of aggregate, bacteria solution, urea, andcalcium chloride. The slurry was then placed in the same design offormwork as described in example 2 with the exception of a change indimension to 3 cm×1.5 cm×5 cm. Effluent valves were shut off to “trap”the solution in the formwork between voids in the aggregate and allowedto set for 3-8 hours.

Another batch of cementation solution with urea and calcium chloride wasprepared and fed to the formwork via gravity feed through the influentholes. As soon as the effluent began to leave the formwork, the effluentvalves were then shut off to “trap” the solution in the formwork betweenvoids in the aggregate for 4-12 hours. This process was repeated 5-10times.

The formwork was then rotated along one axis with the bottom of theformwork now being on top [Side A]. Another batch of cementationsolution with urea and calcium chloride was prepared and fed to theformwork via gravity feed through the influent holes. As soon as theeffluent began to leave the formwork, the effluent valves were then shutoff to “trap” the solution in the formwork between voids in theaggregate for 4-12 hours. This was repeated 5-10 times.

The formwork was then rotated 180 degrees along one axis with the bottomof the formwork becoming the top and the top becoming the bottom.Rotation and administration of cementation solution continued until adesired hardness and strength was reached.

The hardened material in the form of a “brick” was removed from theformwork, washed with tap water and allowed to air dry. All sides werecemented.

Example 4 Lamination Method [Analog]

The lamination method used the same medias and methods as example 2 withthe exception that the aggregate material was placed into the formworkas distinct layers. This enables the final material to have differentdegrees of aggregate particle size distribution, and a more homogeneouscementation within the overall unit.

A 5 mm layer of non-sterile aggregate in the form of indigenous sandfound in Sharjah, UAE was sieved to 600 microns—212 microns and placedinto the formwork. The formwork was lightly vibrated to reduce airbetween aggregates.

2 ml of 55mM CaCl₂ was added to 50 ml of the prepared cementationsolution. The solution was then fed to the formwork via gravity feedthrough the influent holes. The solution was allowed to set in theformwork for approximately 15 minutes.

50 ml of bacteria solution with live cells was then fed to the formworkvia gravity feed through the influent holes. The solution was allowed toset in the formwork for 4-12 hours. Another batch of cementationsolution with urea and calcium chloride was prepared and fed to theformwork via gravity feed through the influent holes. This was repeated5-10 times.

Another layer of 5 mm non-sterile aggregate was placed into theformwork, on top of Layer 1. The process as described for layer 1 wasrepeated until the full height and desired hardness and strength of thefinal unit was reached, with a total of 3 layers.

The hardened material was removed from the bed, washed with tap waterand allowed to dry.

Example 5 Lamination+Rotation Method [3 cm×1.5 cm×5 cm]

The lamination+rotation method used the same medias and methods asdescribed examples 2 and 4, with the exception of each layer beingrotated and treated on both sides prior to the addition of eachsuccessive layer.

Example 6 Lamination Method [Digital Rapidly Manufactured]

A modified “Fab at Home” CNC 3D printer [open source 3D printerplatform] was used to precisely deposit the solutions over a bed of sandmaterial for rapid manufactured tests.

A batch of Solution 1 “Bacteria Solution’ was prepared using the samemethod as example 1. Simultaneously, a batch of Solution 2 “CementationSolution” set to 7.25 pH was prepared using the same media as example 1.

A 5 mm layer of non-sterile aggregate in the form of indigenous sandfound in Sharjah, UAE was sieved to 600 microns—212 microns and placedonto the substrate bed of the 3D Printer.

1 ml of 55mM of CaCl₂ was added to 25 ml cementation solution and mixedwith 25 ml of the bacteria solution. This was then placed in thedeposition syringe of the 3D printer. The syringe motor was controlledvia a computer model and the 51 ml of cells and cementation solution wasprecisely deposited as discrete droplets on top of the sand substrate asmultiple passes. The deposition syringe was reloaded and cleaned asnecessary.

The solutions were allowed to set in the sand for 3 hours, after which anew preparation of cementation solution was prepared and set to 7.25 pH.This new solution was placed into the syringe and deposited over thesand substrate. The solution was allowed to set in the sand for 3 hours,after which a new preparation of cementation solution was prepared andset to 7.25 pH. This process continued for a total of 5 treatments.

A new 5 mm layer of non-sterile aggregate [same composition as layer 1]was sieved to 600-425 microns and evenly placed onto the substrate overlayer 1. The process as described for layer 1 was then repeated forlayer 2 and again for layer 3.

A new preparation of cementation solution was prepared and set to 7.25pH. This solution was placed in the syringe of the 3D printer anddeposited over the top of the hardened sand over multiple passes. Thisstep served as a “finishing” pass of cementation media.

The hardened material was removed from the bed, washed with tap waterand allowed to dry.

While the invention has been described in terms of the aboveembodiments, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theappended claims.

The invention claimed is:
 1. A method for producing constructionmaterial comprising: at least partially filling a formwork with loosepieces of aggregate wherein gaps are formed between at least some of thepieces; preparing a first solution which includes urease which is formedby an enzyme producing bacteria; adding an amount of the first solutionto the loose aggregate; adding an amount of urea and an amount ofcalcium ions to the loose aggregate; the first solution, the urea andthe calcium ions being added to the loose aggregate simultaneously or atdifferent times or in a different order; the calcium ions contributingto the formation of calcium carbonate; the calcium carbonate fills atleast some of the gaps between the loose pieces of aggregate, bonding tothe aggregate and thereby forming a solid material; rotating theformwork; adding an additional amount of first solution to the looseaggregate; adding an additional amount of the urea and calcium ions tothe loose aggregate; the additional amounts of the first solution andthe urea and calcium ions being added to the loose aggregatesimultaneously or at different times or in a different order; andremoving the solid construction material from the formwork.
 2. A methodfor producing construction material as set forth in claim 1 wherein thefirst solution includes an amount of the enzyme producing bacteria.
 3. Amethod for producing construction material as set forth in claim 1wherein the construction material is brick.
 4. A method for producingconstruction material as set forth in claim 1 wherein the enzymeproducing bacteria is taken from the group consisting essentially ofSporosarcina Pasteurii, Sporosarcina Ureae, Proteus Vulgaris, BacillusSphaericus, Myxococcus Xanthus, Proteus Mirabilis, Helicobacter Pylorior a combination thereof.
 5. A method for producing constructionmaterial as set forth in claim 4 wherein the enzyme producing bacteriais Sporosarcina Pasteurii.
 6. A method for producing constructionmaterial as set forth in claim 1 wherein calcium chloride is used as asource of the calcium ions.
 7. A method for producing constructionmaterial as set forth in claim 1 wherein at least some of the gaps areat least five microns wide.
 8. A method for producing constructionmaterial as set forth in claim 1 wherein the urea and calcium ions whichare added to the loose aggregate are in a second solution.
 9. A methodfor producing construction material as set forth in claim 1, furtherincluding filtering the loose pieces of aggregate prior to filling theformwork.
 10. A method for producing construction material comprising:preparing a first solution which includes urease which is formed byenzyme producing bacteria; applying a first layer of loose pieces ofaggregate to a substrate wherein gaps are formed between at least someof the pieces within the first layer; adding the first solution to thefirst layer; adding an amount of urea and an amount of calcium ions tothe first layer; the first solution and the urea and calcium ions beingadded to the first layer simultaneously or at different times or in adifferent order; applying a second layer of loose pieces of aggregate tothe first layer wherein gaps are formed between at least some of thepieces in the second layer and between at least some of the pieces atthe boundary between the first layer and the second layer; adding asecond amount of the first solution to the second layer; adding a secondamount of urea and a second amount of calcium ions to the second layer;the second amount of the first solution and the second amount of ureaand the second amount of calcium ions being applied simultaneously or atdifferent times or in a different order; the calcium ions contributingto the formation of calcium carbonate; the calcium carbonate filling atleast some of the gaps between the pieces of aggregate, bonding to theaggregate, whereby the first and second layers are bonded together and asolid construction material is formed.
 11. A method for producingconstruction material using a computer numerical controlled depositionmachine having at least first, second and third containers comprising:preparing a first solution which includes urease by enzyme producingbacteria; preparing a second solution which includes calcium ions; atleast partially filling the first container with the first solution; atleast partially filling the second container with the second solution;at least partially filling the third container with an amount of loosepieces of aggregate; applying a first layer of loose pieces of aggregatefrom the third container to a substrate; applying a first amount of thefirst solution from the first container to the first layer; applying afirst amount of the second solution from the second container to thefirst layer; applying a first amount of urea to the first layer; thefirst amount of the first solution, the first amount of the secondsolution, and the first amount of urea being applied to the first layersimultaneously or at different times or in a different order; applying asecond layer of loose pieces of aggregate from the third container tothe first layer; applying a second amount of the first solution from thefirst container to the second layer; applying a second amount of thesecond solution from the second container to the second layer; applyinga second amount of urea to the second layer; the second amount of thefirst solution, the second amount of the second solution, and the secondamount of urea being applied to the second layer simultaneously or atdifferent times or in a different order; the calcium ions formingcalcium carbonate; the calcium carbonate filling at least some of thegaps between the pieces of aggregate, bonding to the aggregate, wherebythe first and second layers are bonded together and a solid constructionmaterial is formed.
 12. A method for producing construction material asset forth claim 11, further including filling a fourth container withurea in solution prior to applying the urea to the first layer.
 13. Amethod for producing construction material as set forth in claim 11,further including moving the substrate downwardly prior to theapplication of the second layer on the substrate.
 14. A method forproducing construction material as set forth in claim 11 wherein themulti-layer solid construction material includes a plurality ofindividual units produced substantially contemporaneously by thecomputer numerical controlled deposition machine.
 15. A method forproducing construction material as set forth in claim 12, furtherincluding a dispensing nozzle; the dispensing nozzle connected to thefirst, second, third and fourth containers for applying the firstsolution, the second solution and the urea solution to the first layerand the second layer.
 16. A method for producing construction materialas set forth in claim 15, further including moving the dispensing nozzlehorizontally discrete distances for applying the first, second and ureasolutions at predetermined locations on the first and second layers forforming individual units of construction material.
 17. A method forproducing construction material as set forth in claim 11, furtherincluding filtering the loose pieces of aggregate prior to applying thefirst layer to the substrate.
 18. A method as set forth in claim 17,further including filtering the loose pieces of aggregate prior toapplying the second layer to the first layer.